Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 383 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.922 − 229 =
2. 2.912 − 798 =
3. 3.967 − 579 =
4. 4.788 − 497 =
5. 5.917 − 797 =
6. 6.548 − 417 =
7. 7.534 − 299 =
8. 8.896 − 499 =
9. 9.698 − 198 =
10. 10.824 − 199 =
11. 11.836 − 297 =
12. 12.702 − 598 =
13. 13.948 − 399 =
14. 14.678 − 497 =
15. 15.405 − 119 =
16. 16.765 − 497 =
17. 17.845 − 188 =
18. 18.389 − 369 =
19. 19.874 − 397 =
20. 20.852 − 798 =
21. 21.678 − 468 =
22. 22.886 − 799 =
23. 23.908 − 698 =
24. 24.854 − 499 =
25. 25.828 − 799 =
26. 26.849 − 199 =
27. 27.515 − 397 =
28. 28.815 − 697 =
29. 29.583 − 558 =
30. 30.978 − 797 =
31. 31.986 − 699 =
32. 32.885 − 797 =
33. 33.898 − 569 =
34. 34.664 − 468 =
35. 35.921 − 269 =
36. 36.924 − 599 =
37. 37.601 − 487 =
38. 38.396 − 369 =
39. 39.986 − 478 =
40. 40.619 − 457 =

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